1. Field of the Invention
The present invention relates to a probe-type test handler that is used in the final examination of semiconductor integrated circuits (ICs) in terms of electrical characteristics to accept or reject them and categorize them according to performance.
2. Description of the Related Art
A test handler is an apparatus which feeds electrical signals to respective leads of an IC to perform operational tests, performs the final examination to the IC in terms of electrical characteristics, and determines whether the IC is rejected or accepted, and categorizes the IC according to its performance.
FIG. 11A is a perspective view showing a handler which has been proposed in the past. FIG. 11B is a perspective view showing an IC to be measured. FIG. 12A is a perspective view showing an IC and its socket. FIG. 12B is a cross-sectional view showing the IC and its socket in place.
Shown in FIG. 11A are a loader (in-loader) 1, an inspection section 2 for measuring an IC that is brought in by the loader 1, an unloader (out-loader) 3 for delivering the IC measured at the inspection section 2. The loader 1, the inspection section 2 and the unloader 3 are constructed as follows.
The loader 1 comprises a device pallet 5 for mounting IC 4 thereon, a suction tool 6 for sucking an IC 4 to pick it from the device pallet 5, a loader plotter 7 for moving the suction tool 6 with its IC 4, a rotating table 8 for receiving the IC 4 carried by the loader plotter 7, a suction tool 9 for sucking the IC 4 to pick it from the rotating table 8, a loader plotter 10 for moving the IC 4, sucked by the suction tool 9, to the inspection section 2, and a suction tool 11 for sucking the IC 4 to pick it up on the inspection section 2.
The inspection section 2 comprises a hot plate 13 for receiving the IC 4 brought in from the loader 1 and turning the IC 4 thereon so that the IC 4 is heated to an inspection temperature during a single turn, a test socket 14 provided with contact bars for feeding electrical signals to the leads of the heated IC 4, an adapter socket 15 into which the test socket 14 is inserted for electrical connection, a performance board 16 selectively changed by IC type, and electrically connected to the adapter socket 15, and a measurement module 19 consisting of a test head 17 electrically connected to the performance board 16 and a tester main block 18 electrically connected to the test head 17.
The unloader 3 comprises a stage 20 onto which the IC 4 is temporarily placed after measurement, a suction tool 21 for sucking the IC 4 to pick it up from the stage 20, an unloader plotter 22 for moving the suction tool 21 with the IC 4 in both an X and Y directions, a device pallet 23 onto which an IC 4 determined to be non-defective is placed, and a defective component device pallet 24 onto which an IC 4 determined to be defective is placed.
The operation of the illustrated test handler thus constructed is now discussed.
The suction tool 6 sucks an IC 4 to pick it up from the device pallet 5, and then, the loader plotter 7 is set operative to move the suction tool 6 along with its IC 4 to the rotating table 8.
The rotating table 8 rotates, the loader plotter 10 moves the suction tool 9 over the IC 4 to pick it up, then moves the suction tool 9 along with the IC 4 over the hot plate 13, and then places the IC 4 onto the hot plate 13.
The hot plate 13 is allowed to turn by a single turn, during which the IC 4 is heated to the inspection temperature. The suction tool 11 picks up the heated IC 4. The loader plotter 10 is operated to allow the IC 4 to drop into the test socket 14, and a lead press 12 presses the leads 25 of the IC 4.
FIG. 12A is a perspective view showing the lead press 12, the IC 4, and the socket 14. FIG. 12B is a cross-sectional view showing the state in which the components of FIG. 12A are mounted in place. As shown, the leads 25 of the IC 4 are set onto the tips of the contact bars 26 disposed in the test socket 14, and then firmly pressed on the contact bars 26 by the lead press 12. Electrical signals are fed to the leads 25 of the IC 4 via the contact bars 26 to perform electrical-operation tests.
After the operation tests, the IC 4 is picked up by the suction tool 11, and moved to the stage 20 by the loader plotter 10. A non-defective IC conforming to a predetermined performance requirement is moved to the device pallet 23 by the suction tool 21 and the unloader plotter 22, and an IC falling within a different requirement or a defective IC is moved to the defective component device pallet 24.
In the test handler described above, the lead press 12 presses the tips of the leads 25 against the top of the contact bars 26. Solder of the leads 25 remains stuck to the contact bars 26, or solder sticking takes place.
In a perspective view in FIG. 13A, the tips of the leads 25 of the IC 4 are normal, and in a front view in FIG. 13B, the leads 25 are correctly seated on the contact bars 26 in the test handler. In contrast, as shown in FIG. 13D, solder is peeled off in a needle-like projection which is a so-called solder bridge 27 that forms a short-circuit between leads 25. Furthermore, as shown in FIG. 13C and FIG. 13D, solder deposits in a solder ball 28 which presents poor contact between a lead 25 and its respective contact bar 26. As a result, a good IC may be rejected as defective, and no appropriate inspection in terms of performance may be performed. This problem is even more serious when a multiple pin design with a pin separation of 0.3 mm to 0.5 mm between leads is implemented.
Furthermore, the IC 4 can be inclined with respect to the test socket 14 when both are engaged. This may cause the tip portion of the leads 25 to be bent. The lead press 12 may press the leads 25 onto the contact bars 26 with solder balls or needle-like projections between the leads 25 and the contact bars 26. This may also cause the tip portion of the leads 25 to be bent. Such lead deformation may be a cause for a rejection of IC.
The construction of the apparatus is complex. It comprises the suction tool 9 for picking up and moving an IC, the loader plotter 10, the lead press 12 for measurement, and many more elements.
With the number of leads increasing in multiple pin design, the spacing of the leads 25 is narrowed. Accurate alignment between the leads 25 and the respective contact bars 26 is difficult to achieve and electrical connection may thus suffer from poor contact.